When you close your garage door and it opens back up or refuses to close all the way, there are a few things you can try.
Start by looking at the safety eye sensors that are located on either side of the garage door. The sensors are designed to keep the door from closing all the way if something interrupts the current. Clean the lenses and move everything out of the way. Also, make sure the sensors are lined up.
Adjust the limit switch on your garage door opener. Locate the limit switch on the outside of your opener. It will either look like a screw or knob depending on your model type. The limit switch tells the opener how far to go before it stops. If it is set to far back, there will be a gap when you shut your door. Adjust the limit switch a turn at a time until it is closes the door fully.
Look at the weather stripping on your garage door. If it is coming off the door, it could be getting in the way of the door’s operation. Replace the seal if you see that it is worn out or damaged.
Consider that it may have nothing to do with the door itself. The floor could be the issue. Use a level to determine if your garage floor is sinking.